Isoproterenol-induced desensitization of adenylate cyclase in human astrocytoma cells. Relation of loss of hormonal responsiveness and decrement in beta-adrenergic receptors.

摘要: Incubation of human astrocytoma cells (1321N1) with low concentrations isoproterenol results in a specific loss responsiveness to catecholamines as evidenced by decreased accumulation cAMP intact cells, reduction isoproterenol-stimulated adenylate cyclase activity, and decrease beta-adrenergic receptor density, measured the binding 125I-hydroxybenzylpindolol. The kinetics desensitization suggest involvement two different reactions. initial reaction involves rapid activity little receptors. Subsequently, slower measurable degree both parameters was similar after 24 h desensitization. It is concluded that receptors an event occurs result uncoupling beta-receptor-linked cyclase.